You're looking at this the wrong way. Poker is played with 5 cards, not 2. Starting with 0 cards, being dealt 5 (or 7) random cards, you are more likely to get a straight than a flush.

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If you feel you have a question, dont be lazy; make sure you have asked yourself first. Then search the forum, then just fucking google it to get as much detail as you can. You may then seek clarification on specific points from others.